Service Factor Calculator

Note: These are general engineering guidelines for initial sizing. Always confirm against the gearbox OEM’s service factor tables for your exact model and duty.

Service Factor / Duty Class Picker – Free Online Calculator

Use our Service Factor / Duty Class Picker to estimate the correct service factor (SF) and duty class for your gearbox or drive application. This tool helps engineers, designers, and maintenance teams account for shock loads, operating hours, and duty cycle when sizing motors and gearboxes.

How to Use the Calculator

Follow these steps to select the correct service factor for your application:

Choose Application Type: Select the type of machine you are working with (e.g., conveyor, mixer, pump, hoist). Each has a different baseline service factor.
Select Shock Level: Choose Light for smooth loads, Medium for moderate shock, or Heavy for frequent shock and impact duty.
Enter Starts per Hour: Input the typical number of motor starts per hour. Higher start frequency increases the required service factor.
Enter Daily Operating Hours: Input the number of hours the system runs per day. Longer duty hours require higher service factors due to thermal and wear considerations.
Click Calculate: The tool will instantly recommend a Service Factor (SF) and indicate the Duty Class (Light, Medium, Heavy, Severe).

What the Results Show

Service Factor (SF): A multiplier applied to the required torque to account for duty conditions. Example: if required torque = 100 Nm and SF = 1.6, design torque = 160 Nm.
Duty Class: Categorises your application as Light, Medium, Heavy, or Severe Duty to guide gearbox selection.
Helpful Notes: The tool provides extra recommendations if your application involves high starts, extended hours, or severe shock loads.

Why Service Factor Matters

Selecting the correct service factor is essential to avoid gearbox oversizing or premature failure. Too low a factor may lead to breakdowns under real conditions, while too high a factor can make the design unnecessarily expensive. This calculator gives you a reliable starting point for gearbox and motor sizing, based on industry practice.

Get Started

Enter your application type, shock level, starts per hour, and daily operating hours above. Click Calculate to see the recommended service factor and duty class instantly. For further sizing, use this result alongside our Required Torque Calculator and Output Torque Calculator.